The present invention relates to novel 3-furyl betaoxoalkyl sulfides.
Artificial flavoring agents for foodstuffs have received increasing attention in recent years. In many areas, such food flavoring agents are preferred over natural flavoring agents at least in part because of the uniform flavor that may be so obtained. For example, natural food flavoring agents such as extracts, essences, concentrates and the like are often subject to wide variation due to changes in the quality, type and treatment of the raw materials. Such variation can be reflected in the end product and results in unreliable flavor characteristics and uncertainty as to consumer acceptance and cost. Additionally, the presence of the natural product in the ultimate food may be undesirable because of increased tendency to spoil. This is particularly troublesome in convenience and snack food usage where such products as dips, soups, chips, prepared dinners, canned foods, sauces, gravies and the like are apt to be stored by the consumer for some time prior to use.
The fundamental problem in preparing artificial flavoring agents is that of achieving as nearly as possible a true flavor reproduction. This generally proves to be a difficult task since the mechanism for flavoring development in many foods is not understood. This is notable in products having sweet, meaty and roasted meat flavor and nut-like flavor characertistics. It is also notable in products having vegetable-like and hydrolyzed vegetable protein-like and anise-like flavor characteristics.
Reproduction of roasted, beef brothy, nutty and sweet, meaty flavors and aromas and hydrolyzed vegetable protein-like flavors and aromas has been the subject of the long and continuing search by those engaged in the production of foodstuffs. The severe shortage of foods, especially protein foods, in many parts of the world has given rise to the need for utilizing non-meat sources of proteins and making such proteins as palatable and as meat-like as possible. Hence, materials which will closely simulate or exactly reproduce the flavor and aroma of roasted meat and sweet, meat products, vegetable products and products having nut-like taste are required.
Moreover, there are a great many meat containing or meat based foods presently distributed in a preserved form. Examples being condensed soups, dry-soup mixes, dry meat, freeze-dried or lyophilized meats, packaged gravies and the like. While these products contain meat or meat extracts, the fragrance, taste and other organoleptic factors are very often impaired by the processing operation and it is desirable to supplement or enhance the flavors of these preserved foods with versatile materials which have either roasted meat or sweet meat or vegatable-like or nut-like nuances.
U.S. Pat. No. 3,666,495 provided materials having such desirable meat, roast meat and roasted fragrance and flavor notes. Such materials are organic oxygen containing heterocyclics wherein the second carbon atom from the oxygen atom contains a sulfur substituent and included 3-thia furan compounds having the structure: ##SPC3##
wherein R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are the same or different alkyl or hydrogen. The process disclosed in this patent indicated that such furan 3-thiols and alkyl substituted furan 3-thiols can be produced by the reaction of an appropriate dihydrofuranone-3 or tetrahydrofuranone-3 with hydrogen sulfide in the presence of anhydrous hydrogen chloride at temperatures of -60.degree. C to -100.degree. C.
Nothing in the prior art, however, sets forth implicitly or explicitly the 3-furyl beta -oxoalkyl, sulfides of our invention and their unique and advantageous and unobvious flavor properties.
U.S. Application for Ser. No. 542,830, filed on Jan. 21, 1975, discloses the use in meat flavors of 3-furyl beta chalcogen sulfides having the structure: ##SPC4##
where X is a chalcogen selected from the group consisting of oxygen and sulfur; R.sub.2 and R.sub.3 are each selected from the group consisting of methyl and hydrogen, at least one of R.sub.2 and R.sub.3 being methyl; and R.sub.4 and R.sub.5, taken separately, are each methyl, or R.sub.4 and R.sub.5 taken together are tetramethylene.
The present invention provides novel 3-furyl betaoxoalkyl sulfides useful for altering the organoleptic properties of foodstuffs, a novel process for producing said 3-furyl betaoxoalkyl sulfides as well as methods for altering or enhancing or modifying the organoleptic properties, e.g. taste and aroma, of said foodstuffs.
The novel compounds of our invention are 3-furyl beta-oxoalkyl sulfides having the structure: ##SPC5##
wherein n is 1 or 2 and wherein R.sub.2 and R.sub.3 are each selected from the group consisting of methyl and hydrogen, at least one of R.sub.2 and R.sub.3 being methyl and R.sub.4 and R.sub.5 taken separately, are each lower alkyl, or R.sub.4 and R.sub.5 taken together form a cycloalkyl ring or bi-cycloalkyl ring.
Thus, the 3-furyl beta-oxoalkyl sulfides contemplated within the scope of our invention are, for example:
______________________________________ 3-Furyl-beta-Oxoalkyl Sulfide Compound Structure ______________________________________ (1,3-diethylacetonyl) (2-methyl-3-furyl) sulfide ##STR1## (2-methyl-3-furyl) (3,3,3-trimethyl- acetonyl)sulfide ##STR2## (2-methyl-3-furyl)(1-methyl- 2-oxopropyl)disulfide ##STR3## (2-methyl-3-furyl)(1-methyl- 2-oxopropyl)sulfide ##STR4## (1,3-diethylacetonyl)(2,5- dimethyl-3-furyl)sulfide ##STR5## (Camphor-3-yl)(2-methyl-3- furyl)sulfide ##STR6## (2-methyl-3-furyl)(1,1,3,3- tetramethylacetonyl)sulfide ##STR7## ______________________________________
A number of the 3-furyl beta-oxoalkyl sulfides of our invention (where n=1) may be produced according to a process which comprises the steps of:
i. Carrying out a reaction of a 3-mercapto furan with an oxo-.alpha.-haloalkane, cycloalkane or bicycloalkane (alternatively named: alpha-haloalkanone, cycloalkanone or bicycloalkanone) to form the compounds of our invention according to the following reaction: ##SPC6## PA0 ii. Physically separating said 3-furyl beta-oxoalkyl sulfides from the reaction mass;
wherein X is a halogen selected from the group consisting of chlorine and bromine; wherein R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are defined as above, and wherein M is an alkali metal.
The following table sets forth examples of specific reactants and the resulting products produced using the process of our invention:
TABLE I __________________________________________________________________________ Oxo-alpha-halo alkane or cycloalkane or bicyclo- 3-Furyl-beta-Oxoalkyl alkane reactant 3-furan-thiol reactant Sulfide Compound Structure __________________________________________________________________________ 3-chloro-4-heptanone 2-methyl-3-furan thiol (1,3-dicthylacetonyl) (2-methyl-3-furyl) sulfide ##STR8## 1-chloro-3,3-dimethyl butan-2-one 2-methyl-3-furan thiol (2-methyl-3-furyl) (3,3,3-trimethyl- acetonyl)sulfide ##STR9## 3-chloro-butan-2-one 2-methyl-3-furan thiol (2-methyl-3-furyl)(1-methyl- 2-oxopropyl)sul fide ##STR10## 3-chloro-heptan-4-one 2,5-dimethyl-3-furan thiol (1,3-diethylacetonyl)(2,5- dimethyl-3-furyl) sulfide ##STR11## Camphor-3-yl bromide 2-methyl-3-furan thiol (Camphor-3-yl)(2-methyl-3- furyl)sulfide ##STR12## 2-chloro-2,4-dimethyl- pentan-3-one 2-methyl-3-furan thiol (2-methyl-3-furyl)(1,1,3,3- tetramethylaceto nyl)sulfide ##STR13## __________________________________________________________________________
The reaction of our invention, in order to proceed in a practical manner, takes place using an alkali metal salt of a 3-furan thiol, such as the sodium or potassium salt of 2-methyl-3-furan thiol or the sodium or potassium salt of 2,5-dimethyl-3-furan thiol. The alpha haloalkanone or cycloalkanone or bicycloalkanone may be a bromo derivative or a chloro derivative. Each of the reactants is preferably dissolved in an appropriate reaction solvent, e.g. methanol.
Other solvents, which may be used in carrying out this reaction, are ethanol or isopropanol.
The mole ratio of the reactants, the alkali metal salt of the 3-furan thiol: alpha haloalkanone or cycloalkanone or bicycloalkanone may vary from 1:1 up to 5:1, with a preferred ratio of alkali metal salt of 3-furan thiol: alpha haloalkanone or bicycloalkanone or cycloalkanone of 1:1.
The reaction temperature may vary from about 10.degree. C up to about 100.degree. C. The time of reaction is a function of the reaction temperature with lower reaction temperatures giving rise to longer periods of time of reaction and higher temperatures of reaction giving rise to much shorter periods of time of reaction.
The reaction is preferably carried out at atmospheric pressure, but pressures greater than atmospheric, e.g. 5 atmospheres may be used without detrimentally affecting the yield of product or the time of reaction which is required to obtain such yield.
At the end of the reaction, the reaction product is extracted from the reaction mass using a non-reactive solvent, e.g. n-hexane or methylene dichloride, after the reaction mass is first quenched with water and neutralized with aqueous acid. The solvent extract is then dried, concentrated and distilled preferably by means of vacuum distillation.
A process for preparing the disulfides of our invention involves reacting a 2-alkyl-3-furan thiol with an oxoalkyl or oxocycloalkyl alpha thiol and iodine in the presence of nonreactive solvent e.g., diethyl ether. Thus, for example, (i) 1-mercapto-2-oxo-3-methyl butane is reacted with iodine (as the oxidizing agent) and 2,5-dimethyl-3-furan thiol, thereby forming (2-oxo-3-methyl butyl) (2,5-dimethyl-3-furyl) disulfide; and (ii) 2-oxo-cyclohexylmercaptan is reacted with iodine and 2-methyl-3-furan thiol to form (2-oxocyclohexyl) (2-methyl-3-furyl) disulfide. This reaction takes place in the presence of a base, e.g., an alkali metal carbonate such as sodium carbonate. The mole ratio of I.sub.2 :base:2-alkyl-3-furan thiol:oxoalkyl alpha mercaptan is preferably about 0.75:0.75:0.50:1.0. The reaction may be carried out at temperatures in the range of 10.degree. C up to 35.degree. C with room temperature being most convenient.
The 3-furyl beta-oxoalkyl sulfides of our invention, produced as stated above have useful organoleptic properties giving rise to the use as foodstuff flavors or flavor adjuvants or flavor enhancers as set forth in an illustrative manner in the following table:
TABLE II __________________________________________________________________________ 3-Furyl-beta-Oxoalkyl Sulfide Compound Structure Flavor Properties __________________________________________________________________________ (1,3-diethylacetonyl) (2-methyl-3-furyl) sulfide ##STR14## ##STR15## (2-methyl-3-furyl) (3,3,3-trimethyl- acetonyl)sulfide ##STR16## ##STR17## (2-methyl-3-furyl)(1-methyl- 2-oxopropyl)disulfide ##STR18## Meaty, sweet, yeasty aroma and flavor with hydrolyzed vegetable protein-like and nutty nuances. (2-methyl-3-furyl)(1-methyl- 2-oxopropyl)sulfide ##STR19## ##STR20## (1,3-diethylacetonyl)(2,5- dimethyl-3-furyl)sulfide ##STR21## ##STR22## (Camphor-3-yl)(2-methyl-3- furyl)sulfide ##STR23## Sweet, meaty, crispy aroma and a sweet, (2-methyl-3-furyl)(1,1,3,3- tetramethylacetonyl)sulfide ##STR24## Meaty, sulfury aroma, meaty, roast onion and ulfury flavor with a green note. It also has a garlic and alliaceous nuance __________________________________________________________________________
Thus, the 3-furyl beta-oxoalkyl sulfides produced according to the instant invention can be used to alter, vary, fortify, modify, enhance or otherwise improve the organoleptic properties, including flavor and/or aroma, of a wide variety of materials which are ingested, consumed, or otherwise organoleptically sensed.
The term "alter" in its various forms will be understood herein to mean the supplying or imparting a flavor character or note to an otherwise bland, relatively tasteless substance, or augmenting an existing flavor characteristic where the natural flavor is deficient in some regard, or supplementing the existing flavor or aroma impression to modify the organoleptic character. The materials which are so altered are generally referred to herein as consumable materials.
Such 3-furyl beta-oxoalkyl sulfides are accordingly useful in flavoring compositions. Flavoring compositions are hereintaken to mean those which contribute a part of the overall flavor impression by supplementing or fortifying a natural or artificial flavor in a material, as well as those which supply substantially all the flavor and/or aroma character to a consumable article.
The term "foodstuff" as used herein includes both solid and liquid ingestible materials for man or animals, which materials usually do, but need not, have nutritional value. Thus, foodstuffs includes meats, gravies, soups, convenience foods, malt and other alcoholic or non-alcoholic beverages, milk and dairy products, nut butters such as peanut butter and other spreads, seafoods including fish, crustaceans, mollusks and the like, candies, breakfast foods, baked goods, vegetables, cereals, soft drinks, snack foods, dog and cat foods, other veterinary products, and the like.
When the 3-furyl beta-oxoalkyl sulfides according to this invention are used in a food flavoring composition, they can be combined with conventional flavoring materials or adjuvants. Such co-ingredients or flavoring adjuvants are well known in the art for such use and have been extensively described in the literature. Apart from the requirement that any such adjuvant material is ingestibly acceptable, and thus non-toxic or otherwise non-deleterious, conventional materials can be used and broadly include other flavor materials, vehicles, stabilizers, thickeners, surface active agents, conditioners and flavor intensifiers.
Examples of preferred co-flavoring adjuvants are:
Methyl thiazole alcohol (4-methyl-5-beta-hydroxyethyl thiazole); PA1 2-Methyl butanethiol; PA1 4-Mercapto-2-butanone; PA1 3-Mercapto-2-pentanone; PA1 1-Mercapto-2-propanone; PA1 Benzaldehyde; PA1 Furfural; PA1 Furfural alcohol; PA1 2-Mercapto propionic acid; PA1 Alkyl pyrazine; PA1 Methyl pyrazine; PA1 2-Ethyl-3-methyl pyrazine; PA1 Tetramethyl pyrazine; PA1 Polysulfides; PA1 Dipropyl disulfide; PA1 Methyl benzyl disulfide; PA1 Alkyl thiophenes; PA1 2-Butyl thiophene; PA1 2,3-Dimethyl thiophene; PA1 5-Methyl furfural; PA1 Acetyl furan; PA1 2,4-Decadienal; PA1 Guiacol; PA1 Phenyl acetaldehyde; PA1 .delta. -Decalactone; PA1 d-Limonene; PA1 Acetoin; PA1 Amyl acetate; PA1 Maltol; PA1 Ethyl butyrate; PA1 Levulinic acid; PA1 Piperonal; PA1 Ethyl acetate; PA1 n-Octanal; PA1 n-Pentanal; PA1 Hexanal; PA1 Diacetyl; PA1 Monosodium glutamate; PA1 Sulfur-containing amino acids; PA1 Cysteine; PA1 Hydrolyzed vegetable protein; PA1 2-Methylfuran-3-thiol; PA1 2-Methyldihydrofuran-3-thiol; PA1 2,5-dimethylfuran- 3-thiol; PA1 Hydrolyzed fish protein; and PA1 Tetramethyl pyrazine
The 3-furyl beta-oxoalkyl sulfides or the compositions incorporating them, as mentioned above, can be combined with one or more vehicles or carriers for adding them to the particular product. Vehicles can be edible or otherwise suitable materials such as ethyl alcohol, propylene glycol, water and the like. Carriers include materials such as gum arabic, carrageenan, other gums and the like. The 3-furyl beta-oxoalkyl sulfides according to this invention can be incorporated with the carriers by conventional means such as spray-drying, drum-drying and the like. Such carriers can also include materials for coacervating the 3-furyl beta-oxoalkyl sulfides (and other flavoring ingredients, as present) to provide encapsulated products. When the carrier is an emulsion the flavoring composition can also contain emulsifiers such as mono- and diglycerides or fatty acids and the like. With these carriers or vehicles, the desired physical form of the composition can be prepared.
The quantity of 3-furyl beta-oxoalkyl sulfides utilized should be sufficient to impart the desired flavor characteristic to the product, but on the other hand, the use of an excessive amount of the derivative is not only wasteful and uneconomical, but in some instances too large a quantity may unbalance the flavor or other organoleptic properties of the product consumed. The quantity used will vary depending upon the ultimate foodstuff; the amount and type of flavor initially present in the foodstuff; the further process or treatment steps to which the foodstuff will be subjected; regional and other preference factors; the type of storage; if any, to which the product will be subjected; and the preconsumption treatment, such as baking, frying, and so on, given to the product by the ultimate consumer. Accordingly, the terminology "effect amount" and "sufficient amount" is understood in the context of the present invention to be quantitatively adequate to alter the flavor of the foodstuff.
It is accordingly preferred that the ultimate composition contain from about 0.005 parts per million (ppm) to about 250 ppm of 3-furyl beta-oxoalkyl sulfides or mixtures thereof. More particularly, in food compositions it is desirable to use from about 0.01 ppm to 100 ppm for enhancing flavors and in certain preferred embodiments of the invention, from about 0.01 to 50 ppm of the derivatives are included to add positive flavors to the finished product.
The amount of 3-furyl beta-oxoalkyl sulfides or mixtures thereof of our invention to be utilized in flavoring compositions can be varied over a wide range depending upon the particular quality to be added to the foodstuff. Thus, amounts of one or more derivatives according to the present invention of from about 0.5 ppm up to 80 or 90 percent of the total flavoring composition can be incorporated in such compositions. It is generally found to be desirable to include from about 1 ppm up to about 0.1 percent of the 3-furyl beta-oxoalkyl sulfides in such compositions.
The following examples are given to illustrate embodiment of the invention as it is preferred to practice it. It will be understood that these examples are illustrative and the invention is not to be considered as restrictive thereto except as indicated in the appended claims.
All parts, proportions, percentages, and ratios here are by weight unless otherwise indicated.